INFO: task syz-executor.2:11002 blocked for more than 143 seconds. Not tainted 5.8.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27264 11002 6977 0x20020004 Call Trace: context_switch kernel/sched/core.c:3453 [inline] __schedule+0x8e1/0x1eb0 kernel/sched/core.c:4178 schedule+0xd0/0x2a0 kernel/sched/core.c:4253 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1873 __down_common kernel/locking/semaphore.c:220 [inline] __down+0x183/0x2a0 kernel/locking/semaphore.c:237 down+0x57/0x80 kernel/locking/semaphore.c:61 console_lock+0x25/0x80 kernel/printk/printk.c:2309 do_con_write+0x11e/0x7400 drivers/tty/vt/vt.c:2596 con_write+0x22/0xb0 drivers/tty/vt/vt.c:3159 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0x3ce/0xf80 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046 __vfs_write+0x76/0x100 fs/read_write.c:495 vfs_write+0x268/0x5d0 fs/read_write.c:559 ksys_write+0x12d/0x250 fs/read_write.c:612 do_syscall_32_irqs_on+0x3f/0x60 arch/x86/entry/common.c:403 __do_fast_syscall_32 arch/x86/entry/common.c:448 [inline] do_fast_syscall_32+0x7f/0x120 arch/x86/entry/common.c:474 entry_SYSENTER_compat+0x6d/0x7c arch/x86/entry/entry_64_compat.S:138 RIP: 0023:0xf7f31569 Code: Bad RIP value. RSP: 002b:00000000f5d2c0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000020000500 RDX: 00000000000000f2 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1143: #0: ffffffff89bc1180 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779 1 lock held by in:imklog/6484: #0: ffff8880a920b8f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 4 locks held by syz-executor.2/11002: #0: ffff888093966098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffff888093966130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:888 [inline] #1: ffff888093966130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:911 [inline] #1: ffff888093966130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write+0x280/0x870 drivers/tty/tty_io.c:1046 #2: ffff8880939662e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x1bf/0xf80 drivers/tty/n_tty.c:2316 #3: ffffc90000fb4378 (&ldata->output_lock){+.+.}-{3:3}, at: process_output_block drivers/tty/n_tty.c:550 [inline] #3: ffffc90000fb4378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x4fa/0xf80 drivers/tty/n_tty.c:2333 2 locks held by syz-executor.3/11022: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1143 Comm: khungtaskd Not tainted 5.8.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd7d/0x1000 kernel/hung_task.c:295 kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 11022 Comm: syz-executor.3 Not tainted 5.8.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:write_comp_data+0x2f/0x80 kernel/kcov.c:218 Code: 05 16 4c 8e 7e 65 48 8b 34 25 00 ff 01 00 a9 00 01 ff 00 74 0f f6 c4 01 74 59 8b 86 04 14 00 00 85 c0 74 4f 8b 86 e0 13 00 00 <83> f8 03 75 44 48 8b 86 e8 13 00 00 8b b6 e4 13 00 00 4c 8b 00 48 RSP: 0018:ffffc90015e074d8 EFLAGS: 00000246 RAX: 0000000000000002 RBX: 0000000000000050 RCX: ffffffff83c646a4 RDX: 000000000000002e RSI: ffff888095b42040 RDI: 0000000000000004 RBP: 000000000000002e R08: 0000000000000001 R09: ffff8880a36bf11f R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a002e R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f0ea01d4 FS: 0000000000000000(0000) GS:ffff8880ae700000(0063) knlGS:00000000f5db3b40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000561a60b49358 CR3: 000000009170e000 CR4: 00000000001426e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0x9d4/0x193b drivers/video/fbdev/vga16fb.c:922 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1d5/0x230 drivers/video/fbdev/core/fbcon.c:1381 fbcon_switch+0xb6e/0x16c0 drivers/video/fbdev/core/fbcon.c:2363 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1015 fbcon_modechanged+0x575/0x710 drivers/video/fbdev/core/fbcon.c:3001 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048 fb_set_var+0xae8/0xd60 drivers/video/fbdev/core/fbmem.c:1056 do_fb_ioctl+0x33f/0x6c0 drivers/video/fbdev/core/fbmem.c:1109 fb_compat_ioctl+0x175/0xc10 drivers/video/fbdev/core/fbmem.c:1315 __do_compat_sys_ioctl+0x1d3/0x230 fs/ioctl.c:847 do_syscall_32_irqs_on+0x3f/0x60 arch/x86/entry/common.c:403 __do_fast_syscall_32 arch/x86/entry/common.c:448 [inline] do_fast_syscall_32+0x7f/0x120 arch/x86/entry/common.c:474 entry_SYSENTER_compat+0x6d/0x7c arch/x86/entry/entry_64_compat.S:138 RIP: 0023:0xf7fb8569 Code: Bad RIP value. RSP: 002b:00000000f5db30cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004601 RDX: 0000000020000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000